When an 850 order is brought into Acctivate and Invoiced, the Invoice is automatically selected to be sent back to the partner in an 810 file. If an order is created for an EDI partner in Acctivate manually (without an 850), an option exists to also send these invoices to the partner in an 810 file. This article will show where this option is set.
In Configuration Manager > Edi > Trading Partners, find the partner that you wish to set this option for. Click on the Customer Invoice tab and look for the Invoice Selection option. In Edit Mode, this can be set to EDI Only or Include All. If set to EDI Only, invoices will only be sent in an 810 if the related order was created from an 850 file. If set to Include All, every invoice created in Acctivate for the Customer related to that partner will be selected to be sent in an 810 file.